Polar tweed was discovered in mechanically stressed LaAlO3. Local patches of strained material (diameter ca. 5 μm) form interwoven patterns seen in birefringence images, Piezo-Force Microscopy (PFM) and Resonant Piezoelectric Spectroscopy (RPS). PFM and RPS observations prove unequivocally that electrical polarity exists inside the tweed patterns of LaAlO3. The local piezoelectric effect varies...

This paper is concerned with the development of a piezoelectric d15 shear-induced torsion actuator made of a lead-free piezoceramic material exhibiting giant piezoelectric shear stress coefficient (e15) and piezoelectric transverse shear actuation force comparable to that of lead-based shear-mode piezoceramics. The Mn-modified 0.93(Na0.5Bi0.5TiO3)-0.07BaTiO3 (NBT-BT-Mn) composition exhibited ex...

a r t i c l e i n f o a b s t r a c t A shunted piezoelectric is a device to suppress vibration consisting of a piezoelectric material and a shunt circuit connecting between two electrodes of the piezoelectric material. The sensitivity of damping performances is analyzed for passive shunted piezoelectrics: a resistive, a series resonant, and a parallel resonant shunted piezoelectric. The parame...

In this paper, a feedback control mechanism and its optimization for rotating disk vibration/flutter via changes of air-coupled pressure generated using piezoelectric patch actuators are studied. A thin disk rotates in an enclosure, which is equipped with a feedback control loop consisting of a micro-sensor, a signal processor, a power amplifier, and several piezoelectric (PZT) actuator patches...

In recent years, many researchers have studied vibration suppression of fluttering plates using piezoelectric actuators. Lots of these researchers have focused on optimal placement of piezoelectric patches to obtain maximum controllability. Although mass and stiffness characteristics of bonded patches can alter aeroelastic behavior of fluttering plates, few of them considered the effect of the ...

Methods in detecting damages in structural components and monitoring their health is on the way to develop in today’s technology. Approaches; nondestructive towards the part or with the lowest risk; which locate the damage and even diagnose its size, are accentuating the importance of smart materials. One of these materials are piezoelectric that is used both as transducers and actuators in res...

This paper presents a new approach to vibration reduction of >exible spacecraft during attitude control by using pulse width pulse frequency (PWPF) modulator for thruster Cring and smart materials for active vibration suppression. The experiment was conducted on the Naval Postgraduate School (NPS)’s >exible spacecraft simulator (FSS), which consists of a central rigid body and an L-shape >exibl...

Abstract: In this paper asymptotic models describing the mechanical and electric equilibrium state of two types of smart structures are presented and justified. The first structure consists of an anisotropic elastic thin plate with two surface bonded anisotropic piezoelectric patches and the second one is an anisotropic elastic sandwich thin plate with an inserted anisotropic piezoelectric patc...

In this paper, controlling the location of the tip of an L-shape beam under gravity field is investigated. The beam is covered with piezoelectric patches. The gravity filed moves the tip of beam downward and the actuators with induced voltage move the tip to the previous location. to optimize the best location and voltages for actuators, the particle swarm optimization algorithm code is develop...

Piezoelectric elements connected to shunt circuits and bonded to a mechanical structure form a dissipation device that can be designed to add damping to the mechanical system. Due to the piezoelectric effect, part of the vibration energy is transformed into electrical energy that can be conveniently dissipated. Therefore, by using appropriate electrical circuits, it is possible to dissipate str...